# US 7,745,805 B2 · Product inspection system and a method for implementing same that incorporates a correction factor

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- Number: US 7,745,805 B2
- Document ID: US7745805B2
- Status: Granted
- Kind: B2
- Application number: 11/391,521
- Filed: 2006-03-27
- Published: 2006-11-23
- Granted: 2010-06-29
- Earliest claimed: 2002-06-17
- Assignees: Johnson Thread-View Systems
- Inventors: Stanley P. Johnson; Lawrence J. Zagorsky
- Web page: https://patentgrep.com/patent/US7745805B2

## CPC

- G01B 11/2425: {of screw-threads}
- G01B 11/2433: {for measuring outlines by shadow casting}
- G01N 21/8806: {Specially adapted optical and illumination features}
- G01N 21/952: Inspecting the exterior surface of cylindrical bodies or wires (G01N21/956 takes precedence)
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

A system and method for measuring the physical characteristics of an object is provided, wherein the method includes disposing the object within the sensor optical path of an inspection system, causing a source collimated light beam to propagate along the source optical path to be at least partially incident upon the reflecting device, reflecting the source collimated light beam to create a reflected collimated light beam that propagates along the sensor optical path such that the reflected collimated light beam is at least partially incident upon the object to produce a silhouette, wherein at least a portion of the silhouette is incident upon the sensing device to generate initial image data responsive to the silhouette and processing the initial image data responsive to at least one predetermined algorithm to generate resultant image data responsive to at least one of a plurality of physical characteristics of the object.

## Claims

### Claim 1

An inspection system, comprising:
a collimated light source defining a source optical path, wherein said collimated light source is operable to cause a collimated light beam to propagate along said source optical path;
a sensing device defining a sensor optical path;
a positioning device including a positioning device stage, said positioning device stage movably disposed relative to said sensing device and said collimated light source;
a reflecting device, said reflecting device disposed on said positioning device to be within said source optical path to receive said collimated light beam, said reflecting device causing a reflected collimated light beam to propagate along said sensor optical path to said sensing device, wherein said reflected collimated light beam is incident upon an object disposed within said sensor optical path such that a silhouette of said object is generated and incident upon said sensing device, such that said sensing device generates initial data responsive to at least one of said silhouette and said reflected collimated light beam; and
at least one processing device, wherein said at least one processing device is communicated with said sensing device to receive at least a portion of said initial data, wherein said processing device processes said at least a portion of said initial data responsive to a Correction Factor (CF),
wherein said object is at least one of a symmetrically threaded object and an asymmetrically threaded object and wherein said processing device processes said at least a portion of said initial data responsive to a Correction Factor (CF) to determine at least one pitch diameter of said object.

### Claim 2 (depends on 1)

The system of claim 1, wherein when said object is said symmetrically threaded object said Correction Factor (CF) is at least partially represented by the equation:
CF=2(r cos(t)−R),
wherein CF is the Correction Factor, t is the flank angle, R is a 2-D representation of the Pitch Diameter (PD) in the x-z plane and r is the distance between the z-axis and R.

### Claim 3 (depends on 1)

The system of claim 1, wherein when said object is said asymmetrically threaded object said Correction Factor (CF) is at least partially represented by the equation:
CF
=
(
d
⁢
⁢
1
⁢
⁢
tan
⁢
⁢
(
a
⁢
⁢
1
)
+
d
⁢
⁢
2
⁢
⁢
tan
⁢
⁢
(
a
⁢
⁢
2
)
)
(
tan
⁢
⁢
(
a
⁢
⁢
1
)
+
tan
⁢
⁢
(
a
⁢
⁢
2
)
)
,
wherein CF is the Resultant Correction Factor, d1 is a first partial correction factor for a first flank angle a1 and d2 is a second partial correction factor for a second flank angle a2.

### Claim 4 (depends on 3)

The system of claim 3, wherein at least one of said d1 and d2 is at least partially represented by the equation:
d=2(r cos(a)−R),
wherein d is at least one of said first partial correction factor d1 and said second partial correction factor d2, a is at least one of said first flank angle a1 and said second flank angle a2, R is a 2-D representation of the Pitch Diameter (PD) in the x-z plane and r is the distance between the z-axis and R.

### Claim 5

A method for measuring physical characteristics of an object using an inspection system, wherein the inspection system includes a light source defining a source optical path, a sensing device defining a sensor optical path, a reflecting device disposed to communicate the source optical path with the sensor optical path and at least one processing device communicated with the sensing device, the method comprising:
associating the object with the inspection system such that the object is disposed within the sensor optical path;
operating the inspection system to cause the light source to emit a source collimated light beam propagating along the source optical path to be at least partially incident upon the reflecting device;
reflecting the source collimated light beam via the reflecting device to create a reflected collimated light beam that propagates along the sensor optical path such that the reflected collimated light beam is at least partially incident upon the object to produce a silhouette, wherein at least a portion of said silhouette is incident upon the sensing device to generate initial image data responsive to said silhouette; and
processing said initial image data responsive to at least one predetermined algorithm to generate resultant image data responsive to at least one of a plurality of physical characteristics of the object,
wherein said operating further includes performing a lens distortion analysis.

### Claim 6 (depends on 5)

The method of claim 5, wherein said operating further includes calibrating said inspection system via a predetermined calibration algorithm.

### Claim 7 (depends on 6)

The method of claim 6, wherein said calibration algorithm includes determining at least one of X-axis calibration factors, Y-axis first zero diameter factors, Y-axis second zero diameter factors, a Y-axis second diameter factor, a Y-axis second 180 diameter factor, a Y-axis tangent correction factor and a lens distortion factors.

### Claim 8 (depends on 5)

The method of claim 5, wherein said plurality of physical characteristics include first thread 0° side truncated measurements, second thread 0° side truncated measurements, first thread 180° side truncated measurements and second thread 180° side full form measurements.

### Claim 9 (depends on 8)

The method of claim 8, wherein said first thread 0° side truncated measurements include at least one of minor radius, major radius, pitch radius, lead pitch, lead flank angle, lead trail angle and at least one included angle and wherein said second thread 0° side truncated measurements include at least one of a minor radius, a major radius, a pitch radius and a lead pitch.

### Claim 10 (depends on 8)

The method of claim 8, wherein said first thread 180° side truncated measurements include at least one of minor radius, major radius, pitch radius and lead pitch and wherein said first thread 180° side full form measurements include at least one of a minor radius, a major radius, a pitch radius and a lead pitch.

### Claim 11 (depends on 5)

The method of claim 5, wherein said operating further includes performing a component reliability and repeatability (R&R) measurement, wherein said R&R measurement includes associating a gage with said inspection system such that said gage is disposed within said retention mount and calibrating said inspection system a predetermined number of times.

### Claim 12 (depends on 5)

The method of claim 5, wherein said processing includes displaying said resultant data via at least one of a display device and a printed sheet.

### Claim 13 (depends on 5)

The method of claim 5, wherein said predetermined algorithm is at least partially responsive to the equation,
CF=2(r cos(t)−R),
wherein CF is the Correction Factor, t is the flank angle, R is a 2-D representation of the Pitch Diameter (PD) in the x-z plane and r is the distance between the z-axis and R.

### Claim 14 (depends on 5)

The method of claim 5, wherein said predetermined algorithm is at least partially responsive to the equation:
CF
=
(
d
⁢
⁢
1
⁢
⁢
tan
⁢
⁢
(
a
⁢
⁢
1
)
+
d
⁢
⁢
2
⁢
⁢
tan
⁢
⁢
(
a
⁢
⁢
2
)
)
(
tan
⁢
⁢
(
a
⁢
⁢
1
)
+
tan
⁢
⁢
(
a
⁢
⁢
2
)
)
,
wherein CF is the Resultant Correction Factor, d1 is a first partial correction factor for a first flank angle a1 and d2 is a second partial correction factor for a second flank angle a2.

### Claim 15 (depends on 14)

The system of claim 14, wherein at least one of said d1 and d2 is at least partially represented by the equation:
d=2(r cos(a)−R),
wherein d is at least one of said first partial correction factor d1 and said second partial correction factor d2, a is at least one of said first flank angle a1 and said second flank angle a2, R is a 2-D representation of the Pitch Diameter (PD) in the x-z plane and r is the distance between the z-axis and R.

### Claim 16

A method for correcting aberrations in a component silhouette generated by a component inspection system, wherein the component inspection system includes a light source defining a source optical path, a sensing device defining a sensor optical path, a reflecting device disposed to communicate the source optical path with the sensor optical path and at least one processing device communicated with the sensing device, the method comprising:
associating the object with the inspection system such that the object is disposed within the sensor optical path;
operating the light source to emit a source collimated light beam propagating along the source optical path to be at least partially incident upon the reflecting device;
reflecting the source collimated light beam via the reflecting device to create a reflected collimated light beam that propagates along the sensor optical path such that the reflected collimated light beam is at least partially incident upon the object to produce a silhouette, wherein at least a portion of said silhouette is incident upon the sensing device to generate initial image data responsive to said silhouette; and
processing said initial image data to generate resultant image data, wherein said processing includes,
generating initial Pitch Diameter data to determine an initial Pitch Diameter (PD) responsive to said silhouette,
parameterizing at least a portion of said initial Pitch Diameter and expressing said at least a portion of said initial Pitch Diameter data in a Jacobian Matrix,
solving said Jacobian Matrix responsive to a plurality of physical characteristics of said object to generate Correction Factor (CF) data; and
processing said initial Pitch Diameter (PD) data and said Correction Factor (CF) data to generate resultant Pitch Diameter (PD) data.

### Claim 17 (depends on 16)

The method of claim 16, wherein the method includes a machine-readable computer program code including instructions for causing a controller to implement the method.

### Claim 18 (depends on 17)

The method of claim 17, wherein said machine-readable computer program code is encoded onto a storage medium.

### Claim 19

A computer readable storage medium having computer computer-executable instructions for causing a controller to implement a method for measuring physical characteristics of a component using an inspection system, wherein the inspection system includes a light source defining a source optical path, a sensing device defining a sensor optical path, a reflecting device disposed to communicate the source optical path with the sensor optical path and at least one processing device communicated with the sensing device, the method comprising:
associating the object with the inspection system such that the object is disposed within the sensor optical path;
operating the light source to emit a source collimated light beam propagating along the source optical path to be at least partially incident upon the reflecting device;
reflecting the source collimated light beam via the reflecting device to create a reflected collimated light beam that propagates along the sensor optical path such that the reflected collimated light beam is at least partially incident upon the object to produce a silhouette, wherein at least a portion of said silhouette is incident upon the sensing device to generate initial image data responsive to said silhouette; and
processing said initial image data responsive to at least one predetermined algorithm to generate resultant image data comprising at least one of a plurality of physical characteristics of the object,
wherein said operating further includes performing a lens distortion analysis.

### Claim 20 (depends on 19)

The machine-readable computer program code of claim 19, wherein said machine-readable computer program code is encoded onto a storage medium.